1. Field of the Invention
The present invention relates to dual-band frequency converter units and, more particularly, to a dual-band frequency converter unit that selectively performs frequency conversion of 2.4-GHz high-frequency-band signals or 5-GHz high-frequency-band signals and baseband signals by frequency mixing a local oscillator with both of the high-frequency-band signals.
2. Description of the Related Art
Short-range radio communication systems for, for example, wireless local area networks (LANs), generally communicate using 2.4-GHz frequency-band signals, specifically, signals within the frequency range between 2.412 GHz and 2.472 GHz. The 2.4-GHz frequency-band signals have few restrictions (for example, they require no license for use), and therefore short-range radio communication systems for 2.4-GHz frequency-band signals can be utilized for various applications, such as cell phones, and their range of applications is expanding.
Since the utilization of the 2.4-GHz frequency-band signals has been pushed to the limit in recent years, the availability of 5-GHz high-frequency-band signals, specifically signals within the frequency range between 5.17 GHz and 5.32 GHz, which are ordinarily used only for communication, is being discussed. Some short-range radio communication systems that communicate using 5-GHz high-frequency-band signals have already been put into practical use.
Short-range radio communication systems that communicate using 5-GHz high-frequency-band have been put into practical use. However, since and the prevalence of short-range radio communication systems that communicate using 5-GHz high-frequency-band signals is smaller than that of short-range radio communication systems that communicate using 2.4-GHz frequency-band signals, their applicability is limited. To realize short-range radio communication systems for both of the 2.4-GHz frequency-band signals and the 5-GHz high-frequency-band signals, two kinds of short-range radio communication systems, that is, a short-range radio communication system that communicates using 2.4-GHz frequency-band signals and a short-range radio communication system that communicates using 5-GHz high-frequency-band signals, must be selectively used depending on the situation. This not only requires time and effort, but also increases the production cost.